Contents Reproduction types and fructifications General characteristics Classification Economic importance

1. ASCOMYCOTA
Darshan
SALIENT FEATURES
OF

2. CONTENTS
 Introduction
 General
characteristics
 Reproduction
 Classification
 Economic
importance
 Conclusion
 Reference

3. INTRODUCTION
 Also called as “sac fungi” because their sexual spores, called
ascosporesare
produced inside a sac or ascus
 Monophyletic group
 Largest and most diverse group of fungi
 Includes yeasts, molds and edible mushrooms
 Saprobes, parasites
 Economically important – baking, brewery, antibiotics production

4. GENERAL CHARACTERISTICS
 Ascus- a cell in which two haploid nuclei of different mating types come
together and fuse to form a diploid nucleus, followed by meiosis to
produce haploid sexual spores, the ascospores
 In many species the meiotic division is followed by single round of mitosis,
leadingto
production of eight ascospores within each ascus
 In more advanced members of the group, many asci are produced within a
fruiting
body, the ascocarp
 Production of asexual spores by mitosis
 Asexual ascomycetes in deuteromycota

5. MORPHOLOGY
 Single celled, mycelial or dimorphic
 Cell wall composition: filamentousforms- chitin,
yeasts β-1,3- glucans (chitin restricted to budscars)
 Dimorphism- Saprophytic molds inside host (25°C), unicellular
yeasts outside hosts(37°C)
 Hyphae septate and perforatedsepta
 Woronin bodies – Spherical double membranous structures
 Plectenchyma, prosenchyma and pseudoparenchyma

6. REPRODUCTION
 Vegetaive
 Asexual
 Sexual
 Parasexu
al

7. VEGETATIVE REPRODUCTION
 Fragmentation, fission and
budding

8. ASEXUAL REPRODUCTION
 Through formation of spores- conidia (Gr,conia = dust)
 Asexual, haploid spores, also known as conidiospores and
mitospores
 Contain one nucleus and are products of mitotic celldivisions
 Genetically identical to the mycelium from which they originate
 Formed at ends of specialized hyphae, the conidiophores

9. CONIDIOMATA
 Conidiophores may be produced
inside conidiomata known as
pycnidia (sing. pycnidium) or
acervuli (sing. acervulus)
 A pycnidium is a globose or flask-
shaped pseudoparenchymatous
structure that is lined on inside with
conidiophores
 An acervulus is typically a flat or
saucer- shaped bed of short
conidiophores growing side by side
and arising from a more or less

10. ASEXUAL SPORES

11. SEXUAL REPRODUCTION
 Involves nuclear fusion and meiosis, occurs only in those ascomycetes which
possess
asci
 Mating behaviour may be homothallic (mycelium served from single
ascospore) or
heterothallic (includes outcrossing)
 Plasmogamy of different mating types followed by karyogamy
Gametangial fusion:
 Twomorphologically similar gametangia touch at their tips or coil around each
other
and fuse.The fusion cell develops into ascus

12. CONTD.
Gametangial contact:
 Production of morphologically differentiated uninucleate or multinucleate gametangia called
antheridia and ascogonia
Spermatization:
 Attachmentt of single detached male cell to female reproductive organ (trichogyne or somatic
hypha)
and empties it’s nucleus into receptive cell
Somatogamy:
 Fusion of unspecialized somatic hyphae of two compatible mycelia with nuclei
migrating to the ascogonium through septal perforations

13. DEVELOPMENT OF ASCI

14. ASC
I
Cleistothecium:
 A small hollow, more or less
globose, indehiscent
(prototunicate) ascocarp without
an opening.
 The asci are scattered inside
the structure.
 The fruit wall is called peridium
which is pseudoparenchymatous
 Covered by hyphal outgrowths
called

15. CONTD,.
Perithicium:
 A small rounded or flask shaped
ascocarp
 At maturity it has a definite apical pore
or
opening, the ostiole
 The ostiolar canal is lined by slender,
short, delicate, hair-like sterile growths
called periphysis
 The perithcial wall is called peridium. It
encloses a cavity lined by hymenium

16. CONTD.
Apothecium:
 A disc or saucer-shaped or even a cup-like
structure
 Apothecial ascospores produce an exposed
hymenium at maturity
 The hyphae are interwoven to form a structure
called hypothecium located immediately below
the hymenium
 Both these structures are given structural
support by

17. CONTD.
Pseudothecium:
 Asci are formed within locules of a
preformed
ascostroma
 Asci are bitunicate with two seperable wall
layers that contribute to dehiscence
 Ascostromata can be multilocular or
unilocular
 When they are unilocular it is extremely
difficult to distinguish them from a true
perthicium. Such unilocular ascostroma are

18. CLASSIFICATION
Ascomycetes are classified into 3
subphylaPezizomycoti
naSaccharomycoti
na
Taphrinomycotin
a
Discomycetes
Pyrenomycete
s Lorchels
Caterpillar
fungi3 sub groups
 Archaeascomycetes (includes fission
yeasts)
 Hemiascomycetes (possess naked)
 Euascomycetes

19. ECOLOGY AND SIGNIFICANCE
 Important decomposers in land ecosystem
 Fruiting bodies can be food source for insects,snails and rodents
 Many form mutualistic relationship with algae andcyanobacteria
 Symbiosis with plants- mycorrhizal ascomycetes
 Commensal association with plants- endophytic fungi
Harmful interactions
 Dutch Elm disease caused by Ophiostoma ulmi has led to death of many
elms in
Europe
 Asian Cryphonectria parasitica is responsible for attacking American

20. CONTD.
 Mycotoxins produced by ergot (Claviceps purpurea) and Aspergillus
flavusare
carcimogenic
 Aspergillus and Candida can cause infection in humans

21. CONCLUSION
 Most diverse and largest phylum of lingdom fungi
 Characterized by sexually produced ascospores contained within
ascus
 Includes yeasts, molds and edible mushrooms
 Vegetative reproduction by fragmentation budding and fission
 Asexual reproduction is by means of conidia
 Sexual reproduction involves various type of somatogamy
 Some ascomycetes form crozier to maintain dikaryoticstage
 High economic importance

22. REFERENCES
 Alexopoulas C J and Mims C W,2002 Introductory Mycology 4th edition, Wiley
Eastern ,New Delhi
 John Webster and Roland Weber, 2007. Introduction to Fungi 3rd edition, Cambridge
University
Press
 David Moore, Geoffrey D.Robson,Anthony P.J.Trinci (2011) 21st Century Guidebook
to Fungi. Cambridge University Press.
 B.R.Varishta,A.K Sinha, 2011. Botany for degreestudents: Fungi. S Chand
 https://cals.arizona.edu/classes/plp427L/lab8.html
 https://study.com/academy/lesson/the-economic-importance-of-ascomycota.html
 www.wikipedia.com